Thermoformable panels with a honeycomb core coated on at least one face, preferably on the two opposite faces, with a coating layer are known.
Currently such panels are mainly made by spraying on a honeycomb core plate made of paperboard or the like a mixture of fibers and polyurethane. The technology is known by the name Baypreg. The panels obtained in this manner can be three-dimensionally shaped in a mould by compression molding.
Baypreg technology allows thermoformable panels having a low specific weight and an optimal mechanical strength to be obtained, however they are quite expensive and moreover the operations for spraying the polyurethane on the honeycomb cores involve dirtying problems for the operating members of the product lines.
Currently attempts have been made for obtaining thermoformable panels of the type described above by laminating sheets or films of thermoplastic materials on the faces of the honeycomb core. However such attempts have not lead to considerable results, since, when bending (particularly in hot tests) the coating layers made by lamination or by another type of connection of sheets or films to the core layer are subjected to tensile, compressive and shearing stresses that cause them to be detached from the core plate consequently losing the chemical physical bonds and causing the mechanical properties to cease.
Since this type of panels have a possible use in a great amount of different fields, from automotive to furnishings and furniture, as well as structural elements in the building field, it is of great importance the possibility of obtaining panels of this type, more easy to be fabricated and more cheap, moreover without facing a reduction in the mechanical properties and above all without facing increases of density, namely of the weight for the same mechanical strength with respect to the known panels of the same type.